1. Field of the Invention
This invention relates to brake actuating means for pedal propelled vehicles such as bicycles. Although the invention is also applicable to pedal propelled vehicles having more than two wheels, e.g. tricycles, it will for convenience hereinafter be explained and described in relation to bicycles, which are by far the most common form of such vehicles, without thereby implying any limitation of the scope of the invention to bicycles.
2. Review of the Art
This invention relates to a development of the brake actuating means described in my U.S. Pat. Nos. 4,199,046, 4,313,530, 4,905,803, 4,603,764 and 4,605,110, which are the most pertinent art known to me, particularly the last two patents listed. A further impression of the state of the art relating to actuators of the same general type may be obtained by considering the references discussed in the specifications of those patents are cited during their prosecution.
In the actuators described in my U.S. Pat. Nos. 4,199,046, 4,313,530 and 4,905,803, a one-way clutch element acting on the pedal crankshaft of a bicycle is formed by a spiral coil spring having a central bight engaging a yoke through which braking forces are transmitted, and oppositely handed spiral coils surrounding the crankshaft and extending axially outward along the crankshaft from opposite sides of the yoke. Outward portions of the coils are of relatively lighter gauge and are normally the only portions to engage the crankshaft, thus reducing frictional drag. Development has shown that this arrangement can operate very satisfactorily with very little drag during forward pedalling of the bicycle whilst requiring very little rearward angular motion of the pedals to produce engagement.
Much thought has been given to alternatives to this spring type brake actuator as described in the above patents. For those North American manufactured bicycles that have large bottom brackets (approximately 2 inches inside diameter), my U.S. Pat. Nos. 4,603,764 and 4,605,110 provide alternatives to the above coil type brake actuator. In those patents, there is disclosed a device for operating a brake of a pedal operated vehicle, comprising a brake operating lever projecting through an opening in a pedal crankshaft housing of the vehicle and having an inner end forming a first primary clutch element engageable with part of the circumference of a pedal crankshaft within the housing, a pilot clutch comprising two oppositely wound spring coils connected by a bight engaging a yoke the bight ends of the coils being directed in the direction of forward rotation of the crankshaft, the inner end of the lever having an end extending around the crankshaft circumference in the opposite direction to said yoke, means extending from the said end of the lever and wrapping around the crankshaft so as to form a second primary clutch element engageable with the circumference of the crankshaft at least in a zone opposite to that engageable by the lever, and means transmitting forces from the yoke to the distal end of said first primary clutch portion whereby to wrap the latter onto the crankshaft upon rearward motion of the crankshaft. The linkage in one preferred embodiment comprises a single link pivoted to the yoke in a C-formation, although alternative linkage may be formed by multiple links, a resilient strap, or a strap fastened at both ends to the yoke. In each case, the yoke in conjunction with the linkage provides, on movement of the crankshaft in one direction relative to the yoke, a self-servo effect, causing the shaft to be gripped between the yoke and the jaw, the latter being pulled into engagement with the shaft by the spring. The flexibility of the linkage means that the device can be manipulated to reduce its size during assembly of the actuator into the bottom bracket of the bicycle.
Unfortunately, because of the space limitations in the pedal crankshaft housings formed by the small bottom brackets of non-North American manufactured bicycles, I have not hitherto been able to devise any alternative of comparable performance to my earlier spring type actuator for such bicycles, since it is difficult to assemble and to attain adequate strength in arrangements of the type shown in my U.S. Pat. Nos. 4,603,764 and 4,605,110 if they are utilized with such bicycles.